Method and System for Treating Wastewater

ABSTRACT

Methods and systems for treating brine to produce distilled water and dried NaCl are disclosed. The brine enters a crystallization plant and is heated. Once heated, the brine is circulated to an evaporator. The evaporator increases the concentration of NaCl in the brine to a point about the super saturation level. Once above the super saturation level, NaCl crystals are formed. The larger crystals are circulated to a centrifuge for drying and the smaller crystals are recirculated through the evaporator for continued growth. The NaCl crystals are dried in the centrifuge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. utility patent applicationSer. No. 14/746,756, titled “Method and System for Treating Wastewater,”filed Jun. 22, 2015, which is incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

The present invention relates to methods and systems for processingwastewater. More specifically, the present invention relates toprocessing wastewater, such as that generated when recovering oil andnatural gas, to produce a de-wasted water (water that is no longerconsidered a residual waste and can be stored in fresh waterimpoundments) product meeting or exceeding beneficial use criteria, suchas the required properties of General Permit WMGR123 (PennsylvaniaDepartment of Environmental Protection, 2012). Further, the presentinvention relates to producing dry sodium chloride (salt), lithiumcarbonate and liquid calcium chloride (approximately 20% orapproximately 35%) from processed wastewater for beneficial use.

BACKGROUND OF THE INVENTION

Extracting oil and natural gas from unconventional resources, such asshale gas formations, through the combination of horizontal drilling andhydraulic fracturing has increased at a rapid pace in recent years. TheMarcellus Shale and Utica Shale are sedimentary formations that underliemost of Pennsylvania and West Virginia and extend into parts ofVirginia, Maryland, New York and Ohio. These shale formations are two ofseveral important gas reserves in the United States and together theyare one of the largest natural gas “plays” in the world. A “play” is thegeographic area underlain by a gas or oil containing geologic formation.

Development of these gas plays and other unconventional resourcespresents significant potential for economic development and energyindependence, but also presents the potential for environmental impactson land, water and air. For example, between 10% and 40% of the waterused for hydro-fracturing a gas well typically returns to the surface asflowback, or later as produced water. In addition to fracturing fluidsadded by drillers, this wastewater picks up other contaminants from deepin the Earth.

In some parts of the United States, gas drilling companies typicallydispose of wastewater deep in the ground, by using Class II injectionwells. However, the geology in some locations, such as in Pennsylvania,does not necessarily allow for deep injections. Although municipaltreatment plants previously accepted this wastewater, certain states,such as Pennsylvania, prevent publicly owned wastewater treatmentfacilities (POTWs) from accepting water that has flowed back afterfracturing without a certain level of pretreatment. This restriction isthought to promote the goal of establishing and maintaining a closedloop process for the recycling and reuse of oil and gas liquid wastes.States other than Pennsylvania also restrict the ability ofpublicly-owned treatment works to accept oil and gas wastewaters.

Recently, a number of states have passed regulations to treat processedwastewater having specific properties as a non-waste product. Forexample, General Permit WMGR123 (Pennsylvania Department ofEnvironmental Protection, 2012) identifies specific water qualitycriteria that, if met, will not require wastewater after it is processedto be treated as waste. The specific criteria of Appendix A of WMGR123are reproduced below in Table 1.

TABLE 1 General Permit WMGR123, Appendix A Criteria Property LimitsAluminum 0.2 mg/L Ammonia 2 mg/L Arsenic 10 μg/L Barium 2 mg/L Benzene0.12 μg/L Beryllium 4 μg/L Boron 1.6 mg/L Bromide 0.1 mg/L Butoxyethanol0.7 mg/L Cadmium 0.16 μg/L Chloride 25 mg/L COD 15 mg/L Chromium 10 μg/LCopper 5 μg/L Ethylene Glycol 13 μg/L Gross Alpha 15 pCi/L Gross Beta1,000 pCi/L Iron 0.3 mg/L Lead 1.3 μg/L Magnesium 10 mg/L Manganese 0.2mg/L MBAS (Surfactants) 0.5 mg/L Methanol 3.5 mg/L Molybdenum 0.21 mg/LNickel 30 μg/L Nitrite-Nitrate Nitrogen 2 mg/L Oil & Grease ND pH6.5-8.5 SU Radium-226 + 5 pCi/L Radium-228 Selenium 4.6 μg/L Silver 1.2μg/L Sodium 25 mg/L Strontium 4.2 mg/L Sulfate 25 mg/L Toluene 0.33 mg/LTDS 500 mg/L TSS 45 mg/L Uranium 30 μg/L Zinc 65 μg/L

Accordingly, it is important that public health and the environment areprotected as unconventional resource extraction and productionactivities become a more prominent component of the oil and gas sector.To this end, regulations governing the management of such wastewaterhave been evolving at the state level, resulting in increased wastemanagement costs for the petroleum industry. Moreover, strict treatmenttarget requirements specified in each state for unrestricted-use waterare particularly challenging to meet. In addition, the federalgovernment has also proposed restrictions on receipt of produced watersby POTWs. Aside from the challenges that may be posed by the regulatorylevels for certain contaminants, de-wasting wastewaters from oil andnatural gas production pose other challenges, including but not limitedto the large fluctuation in daily flow rate of the wastewater; thevariation in total dissolved solids (TDS) levels; and variableconcentrations of emulsified oil and methanol.

There is therefore a need in the art for methods and systems and forprocessing oil and gas wastewater with a goal to reuse the processedwater, such as for water used in well fracturing whilerecovering/generating useable byproducts. It would be especiallybeneficial if such wastewater could be processed to produce bothby-products for beneficial use as well as de-wasted water, i.e.unrestricted-use water that is not classified as a residual waste. Theproduction of marketable by-products would reduce the costs oftreatment. The production of de-wasted water would allow for lessburdensome storage, transportation, and reuse or the potential directdischarge of the water keeping it in the hydrologic cycle.

SUMMARY OF THE INVENTION

One embodiment of the invention is a method for treating wastewater. Themethod includes the steps of receiving a wastewater, screening thewastewater to determine the optimal treatment approach, pretreating thewastewater to an acceptable quality for thermal mechanicalcrystallization/evaporation, preheating a portion of the wastewater,feeding the wastewater into an evaporator circulation loop, passing thewastewater through a heating chest, forming NaCl crystals in anevaporation/crystallization unit, circulating smaller NaCl crystals backto the evaporator circulation loop, and separating larger NaCl crystalsout of the evaporation/crystallization unit. The embodiment may beconfigured such that the heating chest is part of the evaporatorcirculation loop. The embodiment may also include a step of washing theNaCl crystals with a condensate to generate a substantially pure NaCl.The substantially pure NaCl may be at least 98% pure. The NaCl crystalsmay be dewatered using a centrifuge or like device.

The embodiment may also include routing centrate/filtrate remainingafter the larger NaCl crystals have been separated back to theevaporation/crystallization unit. The centrate/filtrate may be mixedwith a portion of the wastewater as it is fed to theevaporation/crystallization unit. Vapor from theevaporation/crystallization unit may be passed through a demister and/orother mechanical device to remove water droplets. The vapor may becompressed after the water droplets have been removed. The compressedvapor may be used to heat the wastewater. Condensate from the processmay be used for sealing water and wash water.

The embodiment may also include a screening step to determine if thewastewater has high concentrations of methanol, high concentrations ofoil, or low concentrations of total dissolved solids. Once screened,methanol can be removed from wastewater with high concentrations ofmethanol, total dissolved solids can be concentrated in the wastewaterthat has low concentrations of total dissolved solids, and oil can beremoved from the wastewater with high concentrations of oil. Wastewaterhigh in methanol may be processed in a rectification column, wherein thebottom product from the rectification column is passed to a thermalmechanical distillation/evaporation unit and the methanol from therectification column is stored in a methanol storage tank. The totaldissolved solids can be concentrated using a thermal mechanicaldistillation/evaporation unit. The oil from wastewater high in oil canbe removed by first mixing the wastewater high in oil with an emulsionbreaking chemical. Once mixed, the wastewater/emulsion mixture is passedthrough a centrifuge to break the mixture. Once broken the mixture isallowed separate in a separation tank. The mixture may also be heated toassist in separating the oil from the wastewater.

Wastewater from the evaporation/crystallization unit may comprise acondensate/distilled water and a concentrated mixed brinesolution/mother liquor comprising approximately 18 to 20% CaCl2 purge.The condensate/distilled water may be made suitable for unrestrictedreuse in the oil and gas industry, discharge to surface water under anNPDES permit, or reuse in the treatment process.

The concentrated brine from the evaporation/crystallization unit may bepassed to a cooling tank, where it is available for reuse or furthertreatment in a second stage thermal mechanicalevaporation/crystallization unit to generate a high-purity 35% CaCl₂.

Another embodiment may be a system for treating wastewater that includesa wastewater input line for receiving and segregating wastewater fortreatment, a system for pretreating wastewater to an acceptable qualityfor thermal mechanical crystallization/evaporation, a heat exchangerconfigured to preheat a portion of the pretreated wastewater, anevaporation/crystallization unit configured to receive and evaporatepretreated wastewater, a heating chest, a circulation line configured torecirculate pretreated wastewater from the evaporation/crystallizationunit, through the heating chest, and back into theevaporation/crystallization unit, an NaCl washer connected to theevaporation/crystallization unit and configured to spray pretreatedwastewater into a settling area of the evaporation/crystallization unitto wash NaCl crystals from the evaporation/crystallization unit, and acentrifuge configured to receive NaCl crystals removed from theevaporation/crystallization unit by the NaCl washer and dewater the NaClcrystals.

The system may also include a demister or other mechanical devicesconfigured to receive vapor from the evaporation/crystallization unitand remove water droplets from the vapor. The system may also include acompression unit configured to receive the vapor from the demisterand/or other mechanical devices. The compression unit may includeblowers, compressors, or blowers and compressors. The system may alsoinclude a circulation route configured to route the vapor from thecompression unit to a heat exchanger. In some embodiments, a sealingwater holding tank configured to receive the vapor from the compressionunit. The system may also include an input for receiving steam from anexternal source.

The system may also include a system for routing wastewater to a generalwastewater stream, a low total dissolved solids stream, a high methanolstream, a high oil content stream, and a high solid materials stream.The low total dissolved solids stream includes a thermal mechanicaldistillation/evaporation unit configured to receive wastewater low intotal dissolved solids and a distillation/evaporation unit output linefor receiving distilled water. The high methanol stream includes arectification column configured to receive wastewater high in methanoland a rectification output line connected to the rectification columnfor receiving methanol from the rectification column. The high methanolstream may also include a bottom product line connected to therectification column for receiving wastewater with less methanol thanthe wastewater high in methanol, and a distillation/evaporation unitconnected to the bottom product line for receiving wastewater with lessmethanol than the wastewater high in methanol. The high methanol streammay also include a distillation/evaporation unit positioned up-stream ofthe methanol rectification column, wherein the distillation/evaporationunit removes suspended solids from the wastewater. The high oil contentstream includes a high oil stream line for receiving the wastewater witha high oil content, a centrifuge for emulsion breaking, a gravityseparation tank for receiving an oil water mixture from the centrifuge,and a heated separation tank connected to the gravity separation tank.

Another embodiment may be a method for treating CaCl₂ including thesteps of receiving a fluid comprising approximately 20% CaCl₂,recovering lithium carbonate from the fluid, and processing the fluidthrough a second stage thermal mechanical evaporation/crystallizationunit, wherein the second stage thermal mechanicalevaporation/crystallization unit is configured to generate high-purityapproximately 35% CaCl₂, distilled water and a mixed brine rejectstream.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and B provide a schematic diagram of a wastewater treatmentsystem in accordance with an exemplary embodiment of the presentinvention.

FIG. 2 provides a block diagram of a wastewater treatment systemfollowing pretreating and distilling wastewater in accordance with anexemplary embodiment of the present invention.

FIG. 3 provides a schematic diagram of a biological treatment system 300including an anoxic and aerobic treatment system and a membraneseparation system in accordance with an exemplary embodiment of thepresent invention.

FIG. 4 provides a schematic diagram of a wastewater post-treatmentsystem including ion exchange in accordance with an exemplary embodimentof the present invention.

FIG. 5 provides a schematic diagram of a wastewater post-treatmentsystem including reverse osmosis in accordance with an exemplaryembodiment of the present invention.

FIGS. 6A and B provide a schematic diagram of a crystallization plant inaccordance with an exemplary embodiment of the present invention.

FIG. 7 provides a schematic diagram of a wastewater treatment system inaccordance with an exemplary embodiment of the present invention.

FIG. 8 depicts a graph illustrating the chemical oxygen demand valuesfor the influent, effluent, and loading for an operation of a pilotplant in accordance with the wastewater treatment process depicted inFIG. 7 and employing ion exchange.

FIG. 9 depicts a graph illustrating the ammonia values for the influentand effluent for an operation of a pilot plant in accordance with thewastewater treatment process depicted in FIG. 7.

FIG. 10 depicts a graph illustrating the nitrate values for the effluentfor an operation of a pilot plant in accordance with the wastewatertreatment process depicted in FIG. 7.

FIG. 11 presents a process flow diagram for a wastewater treatmentprocess in accordance with an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention provides methods and systems for producingbeneficial by-products and “de-wasted” water from oil and gas liquidwastewater. “De-wasted” water is water with concentrations ofcontaminants below regulatory-established criteria for the contaminants,such as the criteria of General Permit WMGR123, Appendix A (PennsylvaniaDepartment of Environmental Protection, 2012), provided in Table 1above. The systems and processes described herein may be employed toprocess wastewater containing contaminants, such as but not limited to,high total suspended solids (TSS), ammonia, nitrates/nitrites, chemicaladditives, high total dissolved solids (TDS), metals, and/or technicallyenhanced naturally occurring radioactive materials (TENORM). Forexample, the treatment methods may be employed to treat nearly any typeof oil and gas wastewater, including but not limited to top-holewastewater, pit wastewater, spent drilling fluids, flowback fromhydraulic fracturing, produced wastewater, gathering line wastewater andcompressor station wastewaters.

FIGS. 1A and B provide a schematic diagram of a wastewater treatmentprocess 100 in accordance with an exemplary embodiment of the presentinvention. Referring to FIGS. 1A and B, many aspects of the depictedprocess may be modified or altered to produce a distilled water productfrom wastewater from oil or natural gas production. The process shown isexemplary and is intended to show broadly the relationship between thevarious aspects of the wastewater treatment processes 100. As shown,incoming wastewater is transported from an oil or gas well site and/orassociated infrastructure. For example, oil and gas wastewater mayinclude liquid wastes from the drilling, development and/or operation ofoil and gas wells and/or collection systems and facilities. In thisexemplary process, the wastewater may be transported by a tanker 101. Inother embodiments it may be delivered to the treatment facility by pumpsand/or pipelines connected directly or indirectly to a wastewatersource. Wastewater from tanker 101 is routed according to its expectedcomposition. A wastewater profile form is established for each type ofwastewater brought to the facility. The profile forms provide operationsstaff with the qualitative and quantitative characteristics of thewastewater that may be brought to the facility, along with miscellaneousgenerator information. All wastewater profile report forms are kept onfile at the facility. Before any raw, untreated liquid waste is unloadedinto the partially below grade concrete receiving water storage tanks,it is first evaluated/screened by operators. The water is evaluated andscreened using a collection of methods to regulate incoming waste loads.These methods are focused on determining if the incoming material istreatable at the facility and to allow for rejection of material thatthe facility is not allowed to accept per the permits that are in placefor that facility. The water is tested for a set of parameters,including total dissolved solids (TDS)/conductivity, pH, temperature,sulfate, barium, specific gravity, settleable solids, methanol content,radiation exposure rate, as well as visual inspection for oil and otheradditives. If it passes the preliminary characterization and visualinspection screening, the truck may be unloaded into one of the fourconcrete receiving water storage tanks or directly to one of the holdingtanks at the direction of operators. In the exemplary embodiment ofFIGS. 1A and B, the wastewater screening is used to determine theoptimal treatment process. For example, wastewater considered generalwastewater—wastewater that does not have high concentrations of oil ormethanol—may be routed directly to raw water storage tanks 102. Rawwater storage tanks 102 are sized to hold wastewater until it isprocessed. The timing of the process depends on a number of factors,such as amount of wastewater and output demands. Drilling fluids mayalso be routed to screening and washing pits 103 when they have a highconcentration of suspended solids or in another embodiment directly tosludge storage tanks 115. Wastewater from screening and washing pits 103is then routed to raw water storage tanks 102. Sludge and solidsseparated from wastewater at screening and washing pits 103 are routedto sludge storage tanks 115 for further processing.

Incoming wastewater may also be routed for methanol (MeOH) treatmentwhen it contains an elevated concentration of methanol. For purposes ofthe preferred embodiment discloses in FIGS. 1A and B, wastewater isconsidered to have an elevated concentration of methanol when it has amethanol concentration greater than 500 mg/L (methanol containing). Formethanol treatment, the wastewater is processed through primary settlingclarifier 104. Once the solids present in the wastewater are allowed tosettle, it may be transferred to methanol storage holding tanks 105. Themethanol wastewater may also be sent through pretreatment prior to beingsent to the methanol storage holding tanks 105.

From methanol storage holding tanks 105, methanol containing wastewateris passed through cartridge filter 106 to remove residual suspendedsolids. From cartridge filter 106, wastewater is then routed torectification column 107. Bottom product from rectification column 107,which consists of wastewater mostly free of methanol, is routed to amechanical vapor recompression (MVR) distillation or other thermalmechanical distillation/evaporation unit 109 b for further processing.The methanol from the rectification column is routed to methanol storagetank 108, where it is available for beneficial reuse. In anotherembodiment, the methanol wastewater may be put through pretreatment andthermal mechanical distillation/evaporation prior to the rectificationcolumn 107.

Wastewater that contains appreciable quantities of oil or oil skimmedfrom various storage tanks may be treated in an oil processing system toremove the oil before further processing. In the embodiment shown, theoily wastewater is routed to one of two gravity separation tanks, 110 or111, where it is allowed to naturally separate. Wastewater that ismostly free of oil is routed from the gravity separation tanks, 110 or111, to wastewater receiving tanks 102. Wastewater that still has asignificant amount of oil is routed to heated tank 112, where it isheated. Optimally, the wastewater in heated tank 112 is maintained atapproximately 140 to 150 degrees Fahrenheit. However, other temperaturesmay also be used. Once heated, the oily wastewater is allowed tonaturally separate. The wastewater that is mostly free of oil is routedfrom heated tank 112 to wastewater receiving tank 102. The recovered oilmay then be routed to recovered oil tank 113. The recovered oil in tank113 is shipped off-site for other uses including energy recovery. Inanother embodiment, wastewater containing oil may be treated withemulsion breaking chemicals and processed through a centrifuge 137 priorto being introduced to gravity separation tanks 110 a and 111 a.

Produced and flowback wastewater from receiving tank 102 passes throughone or more primary settling clarifiers 114 and raw water storage tanks116 before being routed to a first pretreatment train (items 117, 118,and 119) or second pretreatment train (items 120, 121, and 122) operatedin series or in parallel. In the pretreatment trains, some combinationof one or more chemicals (sodium sulfate, lime, soda ash, ferricchloride) are added to precipitate metals and the pH of the wastewateris adjusted (using caustic and/or hydrochloric acid) in pHadjustment/chemical addition tanks 117/120 to optimize pretreatment.Once the chemicals are added and pH is adjusted, the wastewater passesthrough a flocculation tank where polymer is added to promoteprecipitation and then on to a secondary clarifier (circular or lamellaclarifiers may be used) 118/121 before being sent to a finalequalization tank 119/122. Chemical dosages are continuously adjusted toachieve pretreated water quality that optimizes the opportunities forbeneficial use of by-products and the performance of subsequenttreatment processes.

Generally, solids entrained in the wastewater are removed from thewastewater at the screen washing pit 103 or any of the primary settlingclarifiers 114, or any of the secondary circular or lamella clarifiers118/121. The solids are sent to sludge storage tanks 115. The thickenedsludge is then passed through a filter press 113 a, a rotary press 113b, centrifuge 113 c or other dewatering process, before it istransported to a landfill for disposal. The liquid removed from thesolids in sludge thickening tanks 115 (or other steps in the dewateringprocess) may be recycled to the beginning of the first and/or secondpretreatment trains. Alternatively, the water removed during the sludgedewatering process may be routed to receiving tanks 102.

In one embodiment, wastewater that is low in TDS (typically less than150,000 mg/L) may be routed to a dedicated low TDS pretreatment train.In this embodiment, low TDS wastewater may be stored in receiving tank102 a. The low TDS wastewater may be passed through one or more primarysettling clarifiers 114 a and raw water storage tanks 116 a before beingrouted to pH adjustment/chemical addition tanks 117 a, a secondaryclarifier 118 a, and a final equalization tank 119 a, as discussedabove. As can be seen in FIGS. 1A and B, the pretreated low TDSwastewater may be routed to distillation/evaporation feed tanks 109 aand then on to a thermal mechanical distillation/evaporation unit 109 b,such as but not limited to a NOMAD evaporator. Distilled water fromthermal mechanical distillation/evaporation unit 109 b is routed to adistilled water storage tank 127. Brine from the thermal mechanicaldistillation/evaporation unit 109 b is routed to pretreated waterstorage tanks 124 c, 124 d. In another embodiment, the low TDSwastewater may be routed past the pretreatment stage directly to thermalmechanical distillation/evaporation feed tanks 109 a and then on tothermal mechanical distillation/evaporation unit 109 b for furtherprocessing.

Once the wastewater is passed through one of the pretreatment trainsdescribed above, it may be referred to as “pretreated water” and may besent to a pretreated water polishing treatment 123, 123 a. Waterpolishing treatment 123, 123 a treats the pretreated water using an ionexchange system, ultrafiltration system, or other known methods. Theultrafiltration system may apply hydrostatic pressure to force thepretreated water through semipermeable membranes. Suspended solids areretained in the membrane, while the wastewater passes through themembrane. In another embodiment, the pH of the wastewater may besequentially adjusted using acid addition to promote carbonate removaland reduce scale formation potential followed by caustic addition toobtain the optimum pH for further treatment. Pretreated water passingthrough water polishing treatment 123, 123 a is then stored inpretreated water storage tanks. In the embodiment shown, the pretreatedwater is stored in storage tanks according to TDS. Low TDS (typicallyless than 150,000 mg/L) can be stored in interior storage tanks 124 a orexterior storage tanks 124 b. High TDS (greater than 150,000 mg/L) canbe stored in interior storage tanks 124 c or exterior storage tanks 124d. Alternatively, depending on the system demands, some or all of thepretreated water may be passed from water polishing treatment 123 backto an earlier point in the process. In the embodiment shown, thepretreated water is passed back to raw water storage tank 116. Theamount of water routed to an earlier point in the process depends inpart on the solids content of the incoming wastewater. For example,wastewater high in suspended solids may need to be wetted with rawwastewater (low in suspended solids) or pretreated water to allowconveyance of the wastewater in an optimal manner. Water in pretreatedwater storage tanks may be further processed or made available forbeneficial reuse. Pretreated water may be segregated based on TDSconcentration.

The pretreated water passes from water storage tanks 124 c, 124 dthrough pipe 133 to an evaporation/crystallization unit 125, such as butnot limited to an MVR crystallizer to produce “distilled water”(sometimes referred to as “condensate”), salt (sodium chloride—NaCl) andconcentrated calcium chloride (CaCl₂) brine. Wash water from distilledwater tank 127 is also supplied to the evaporation/crystallization unit125 by way of pipe 134. In certain embodiments, theevaporation/crystallization unit 125 is an MVR crystallizer. Distilledwater produced in the evaporation/crystallization unit 125 is stored ina distilled water tank 127. Concentrated (approximately 20%) calciumchloride brine purge from the evaporation/crystallization unit 125 isrouted to concentrated brine holding tank 136. Dry salt removed by theevaporation/crystallization unit 125 may be made available forbeneficial use. Dry in this context means less than 3% moisture. Anembodiment of the evaporation/crystallization unit 125 is described inmore detail in FIGS. 6A and B.

Salt that precipitates from the calcium chloride brine in the brineholding tank 136 is pumped as slurry back to one of the pretreated waterholding tanks, or to one of the raw water holding tanks where itdissolves allowing recycle back to the evaporation/crystallization unit125.

In another embodiment, the approximately 20% calcium chloride brine maybe processed through a lithium recovery process prior to reuse, disposalor further processing.

Brine from concentrated brine holding tank 136 may also be routed to asecond stage thermal mechanical evaporation/crystallization unit 126 toproduce a more concentrated calcium chloride (approximately 35%),distilled water and solid crystals (primarily barium, strontium andsodium chloride). The second stage thermal mechanicalevaporation/crystallization unit 126, in certain embodiments is acirculation type cooling crystallizer. Distilled water from the secondstage thermal mechanical evaporation/crystallization unit 126 is routedto distilled water storage 127 via pipe 135. Solid crystals from thesecond stage thermal mechanical evaporation/crystallization unit 126 maybe directed to a landfill for disposal. Liquid CaCl₂ may be routed fordirect beneficial use or dried further to make calcium chloride pillsfor beneficial use.

As described in greater detail below, in connection with FIG. 2, thedistilled water is passed to a de-wasting system 128 to make thedistilled water suitable for unrestricted use or direct discharge. Inthe embodiment shown, the de-wasting system 128 includes an anoxic andaerobic treatment system 129, a membrane separation system 130, an ionexchange system 131, and a reverse osmosis (RO) system 132.

As shown, in certain embodiments, a concentrated brine purge holdingtank 136 may be employed along with evaporation/crystallization unit125. In the embodiment shown, evaporation/crystallization unit 125 isfed pretreated wastewater to generate sodium chloride, distilled waterand concentrated calcium chloride (approximately 20%) brine purge. Asnoted above, the distilled water produced in evaporation/crystallizationunit 125 is stored in the distilled water tank 127, and purge producedin the evaporation/crystallization unit 125 flows through a cooling tankand is then stored in the concentrated brine holding tank 136 and thenrecycled for use in drilling, development and/or operation of oil andgas wells, or fed to a second stage the second stage thermal mechanicalevaporation/crystallization unit 126 to generate more distilled water,solid crystals (primarily barium, strontium and sodium chloride) andmore concentrated high-purity calcium chloride (approximately 35%)solution. As an alternative, the approximate 20% calcium chloride brinepurge may be augmented by addition of dry calcium chloride to bring itto approximately 35% without additional evaporation/crystallization. Theapproximately 35% calcium chloride solution may be recycled for use indrilling, development and/or operation of oil and gas wells or used inother commercial/industrial activities.

In another embodiment, the approximately 20% calcium chloride may beprocessed through a lithium recovery process prior to being reused,further processed or augmented.

Although distilled water produced by the above described process may bereused in drilling, development and/or operation of oil and gas wellswithout further processing, it typically must still be treated as awaste product. In Pennsylvania, such waste must be stored inimpoundments, tanks or containers that meet residual waste requirementsprior to future use as makeup water for hydraulic fracturing or otheroil and gas well development activities. Accordingly, storage,transport, and reuse of such a material may be burdensome and costly ascompared to a non-waste product. Further processing must be done to“de-waste” the water.

As shown in Table 2, below, distilled water produced by processingwastewater through a system similar to the system illustrated in FIGS.1A and B, may not meet each of the criteria for a de-wasted waterproduct, such as the criteria listed in Table 1 which representde-wasted water criteria for Pennsylvania.

TABLE 2 Summary of Distilled Water Characteristics Nitrite/ AlkalinityTotal Ammonia Nitrate, Flow (mg/L TDS TSS COD CBOD5 Nitrogen NH3—N NOx—N(MGD) pH CaCO₃) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (m/L) Average0.04 10.2 139 50 7 1257 439 47 31.9 0.25 Min. 0.002 8.1 134 6 5 211 8626 7.3 0.25  5% 0.006 9.7 135 13 5 234 112 30 15.2 0.25 25% 0.015 10.0137 21 5 363 222 37 24.6 0.25 50% 0.035 10.2 139 39 5 738 306 46 32.80.25 75% 0.051 10.4 142 75 6 1628 552 55 37.7 0.25 95% 0.095 10.6 144121 14 3404 958 63 55.1 0.25 Max 0.119 10.7 144 138 31 7900 1220 90 59.40.56

As shown in Table 2, the content of organic compounds in the water, asshown by the chemical oxygen demand (COD) value, are of particularimportance, as the values in Table 2 greatly exceed the limit for CODshown in Table 1. Organic compound concentrations may be determined byCOD and/or biological oxygen demand (BOD) values, which indicates themass of oxygen consumed per liter of solution. Another importantcontaminate when evaluating the distilled water against de-wasted watercriteria is nitrogen series contaminants, including ammonia (NH₃),nitrite, and/or nitrate.

Generally, ammonia, COD, and BOD concentrations in the distilled waterproduced from pretreating and distilling wastewater from oil and naturalgas operations as shown in FIGS. 1A and B may be present at levelssimilar to domestic sewage. The median ratio of CBOD₅ to COD as shown inTable 2 is about 0.5, which may be indicative of a fairly biodegradablewastewater. Moreover, the COD may consist of low molecular weightorganics and/or volatile organic compounds, as the organic materialspassed through the water polishing treatment 123.

The ammonia and total nitrogen concentrations of the distilled water mayalso be similar to domestic wastewater. As shown in Table 2, the totalnitrogen levels of a distilled water product produced from pretreatingand distilling wastewater from oil and natural gas operations may rangefrom about 20% to about 90% higher than ammonia levels. Because thenitrate/nitrite levels are shown to be low (e.g., about 0.25 mg/L), thetotal nitrogen and ammonia likely represent an organic nitrogenfraction, which may or may not be biodegradable.

FIG. 2 provides a block diagram of a de-wasting system 128 followingpretreating and distilling wastewater in accordance with an exemplaryembodiment of the present invention. The illustrated system is capableof producing de-wasted water meeting or exceeding each of thecharacteristics of a typical regulatory regime for de-wasted water, suchas Pennsylvania's WMGR123. Such a system solves many of the problems ofde-wasting distilled water, including but not limited to the similardensity of oil, mud and water; large fluctuation in daily flow rate; andhigh concentrations of emulsified oil.

Referring to FIGS. 1A, 1B and FIG. 2, distilled water, such as waterstored in the distilled water tank 127, passes into a temperaturecontrol unit 205 (not shown in FIGS. 1A or B), such as a heating orcooling system. The temperature of the influent distilled water ispreferably between 20° C. to 35° C. for the present invention toadequately treat the water. One or more temperature control units 205are employed to either heat or cool the water to a temperature withinthe preferred range. Water temperature instrumentation determines thewater temperature of the inlet and outlet water from the temperaturecontrol units 205.

Once the temperature of the influent distilled water is within anacceptable range, the water may be passed through a pre-filter 210, suchas but not limited to a basket strainer or the like. The pre-filter 210removes particles from the water having a size of greater than about1/20 inch, greater than about 1/16 inch, greater than about ⅛ inch, orgreater than about ¼ inch. Solids collected in the pre-filter 210 (orgenerated in subsequent processes described below) may be managed inaccordance with applicable residual waste regulations.

The distilled water passes from the pre-filter 210 to a biologicaltreatment system 300. The biological treatment system 300 comprise ananoxic and aerobic treatment system 129 and a membrane separation system130. As shown, distilled water is passed from the pre-filter 210 to theanoxic and aerobic treatment system 129, which comprises one or moreanoxic reactor tanks and aerobic reactor tanks to remove COD/BOD andnitrogen. Following treatment in the anoxic and aerobic treatment system129, the treated water moves to a membrane separation system 130comprising one or more membrane separation tanks. The anoxic and aerobictreatment system 129 and membrane separation system 130 of thebiological treatment system 300 are described in greater detail inconnection with FIG. 3, below. Following processing in the anoxic andaerobic treatment system 129 and the membrane separation system 130, theprocessed water stream is further treated in either an ion exchangesystem 131 or a reverse osmosis system 132. Alternatively, as shown inthe embodiment of FIGS. 1A and B, the processed water stream may betreated by the ion exchange system 131, reverse osmosis system 132, orboth. The ion exchange system 131 and reverse osmosis system 132 aredescribed in greater detail below in connection with FIGS. 4 and 5,respectively.

FIG. 3 provides a schematic diagram of a biological treatment system 300including an aerobic and anoxic treatment system (FIG. 2 at 129)comprising a pre-anoxic tank 310, an aeration tank 320 and a post-anoxictank 320; and a membrane separation system (FIG. 2 at 130) comprising amembrane bioreactor 340. Referring to FIGS. 1A and B, 2, and 3, a liquidwater stream, such as the distilled water stored in the distilled watertank 127, enters a pre-anoxic tank 310 from the pre-filter 210 throughpump 305, where a denitrification reaction occurs. Denitrification is amicrobial process where nitrate (NO₃ ⁻) is converted to nitrite (NO₂ ⁻),which is converted to nitric oxide and nitrous oxide (NO+N₂O), which isconverted to nitrogen gas (N₂). The liquid water stream is added to thepre-anoxic tank 310 in a continuous process.

The pre-anoxic tank 310 is “seeded” with biological material thatincludes bacteria. The bacteria (e.g., heterotrophic bacteria) in thepre-anoxic tank 310 convert any nitrate compounds in the wastewater tonitrogen gas, which is released into the atmosphere. Althoughdenitrification releases nitrogen from the water, oxygen released in theprocess stays dissolved in the water, which reduces the oxygen inputneeded for the system in the next step of the process. The source of thebiological material is sludge from a sewage processing plant, typicallyreferred to as “activated sludge.” Activated sludge includes sludgeparticles produced in waste treatment by the growth of organisms inaeration tanks, such as in a sewage treatment plant. The sludge is“activated” because the sludge includes living material such asbacteria, fungi, and protozoa. These living materials are used in thedenitrification reaction. This seed step occurs once, to seed the tank.Then, additional bacteria is grown as part of the COD degradationprocess. In some cases, all of the bacteria in the system may die. Inthat case, the system must be re-seeded.

In the embodiment of FIG. 3, the pre-anoxic tank 310 includes asubmersible mix pump 311 for mixing the tank contents. Optionally,additives such as but not limited to phosphorous may be added to thepre-anoxic tank 310. Phosphorus is an essential nutrient required forbiological treatment which is missing in the wastewater. For example,phosphorus, in the form of phosphoric acid stored in tank 358 is added,through pump 353, as needed to the influent of pre-anoxic tank 310.Typically, a dissolved oxygen level in the anoxic tank may be from aboutgreater than 1.0 mg/L and the temperature in the pre-anoxic tank 310range from about 20° C. to about 35° C. An industrial scale pre-anoxictank may be about 10,000 gallons of capacity, without limitation.

The distilled water being processed in the biological treatment system300 passes from the pre-anoxic tank 310 to an aeration tank 320 suchthat nitrogen compounds (e.g., NH₃, NO₂₎ are nitrified by nitrifyingbacteria. Nitrification is the oxidation of ammonia with oxygen intonitrite followed by the oxidation of these nitrites into nitrates bybiological mechanisms, such as by bacteria or other micro-organisms.Under aerobic conditions, biological organisms (e.g., ammonia oxidizingbacteria and/or nitrite oxidizing bacteria) added in the pre-anoxic tank310 and remaining in the water that passes to the aeration tank 320oxidize nitrogen compounds to nitrite and nitrate compounds.

Oxygen is added to the aeration tank 320, for example by employingcompressors and/or diffusers or by high purity oxygen and mechanicalsurface aeration. As shown in FIG. 3, an air pump 321 delivers air intothe aeration tank 320, and a pocket of compressed air forms in the topof the aeration tank 320. As water enters the tank from the pre-anoxictank 310, it passes through the air pocket. For example, the aerationtank 320 may contain a baffle or other structure, such that water spraysdown through the pocket of compressed air. Moreover, water may befurther aerated in the tank through a riser or the like (not shown). Forexample, coarse bubble diffusers may be submerged in the tank liquid andprovide air to the aeration tank 320.

An industrial scale version aeration tank 320 may be from about 50,000to about 75,000 gallons, without limitation. The tank may include a ventsystem (not shown) to release gases that form in the tank and to providefor a turnover of air in the tank. The pump 321 and vent may becontrolled by the same electrical circuit such that vent may open whenthe pump 321 is running, and the vent may close when the pump is turnedoff. Moreover, the pump 321 and vent circuitry may be in electricalcommunication with a pressure gauge so that they may be automaticallyoperated based on the pressure within the tank. In other embodiments,the pump 321 and vent circuitry may be in communication with a flowswitch, which turns the pump/vent system on when water is flowing.

As shown, any number of chemicals may be added to the aeration tank 320.Bacteria macronutrients, such as but not limited to phosphorous, may beadded at any point in the anoxic/aerobic biological treatment system.For example, phosphorus, in the form of phosphoric acid stored in tank358 is added, through pump 353, as needed, to aeration tank 320.

Micronutrients may be added by directing, for example, boiler or coolingtower blow-down to the system along with a source of alkalinity (e.g.,NaOH) for pH control, as nitrification consumes alkalinity. Thealkalinity source may be KOH, instead of or in addition to NaOH incertain embodiments, due to the very low Cl⁻ and Na⁺ limits forde-wasting water in some regulatory regimes, such as the limits shown inTable 1. For example, boiling or cooling tower blow-down from thetemperature control unit 205 with added NaOH or KOH is stored in tank357 and added by pump 352. Typically, antifoam agent addition may beneeded to control foaming, depending on the characteristics of thedistilled water. Accordingly, an antifoam agent stored in tank 356 maybe added to the aeration tank 320 by pump 351.

Nitrate may be recycled to the pre-anoxic tank 310 from the aerationtank 320 through a dedicated recycle pump 322 or the like. In this way,the oxygen requirement of the waste in the pre-anoxic tank 310 is met bythe release of oxygen from nitrates in the recycled flow.

The treated distilled water passes from the aeration tank 320 to apost-anoxic tank 330, where residual nitrate (e.g., from about 3 toabout 10 mg/L) is removed by microbial action. In some cases, the carbonconcentration in the water may be insufficient to support this microbialaction. In those cases, carbon is added from dosing the post-anoxic tank330 with a supplemental carbon source, such as ethanol, which is storedin tank 359 and delivered by pump 354. The use of a supplemental carbonsource may not be necessary in all cases. Such a source may be employeddue to low BOD/COD levels in the treated water. The amount of addedcarbon varies with the design influent loading, which can vary fromsystem to system. The amount of carbon in the system should besufficient to maintain bacterial growth, such as to prevent the bacteriafrom dying off and requiring the system to be re-seeded.

Denitrification requires a carbon source to take place. Althoughsufficient carbon may be available in the distilled water entering thepre-anoxic tank 310, the BOD:N ratio of the material entering thepost-anoxic tank 330 may be insufficient to allow for adequatedenitrification. Accordingly, an external source of carbon (e.g.,methanol, ethanol, etc.) may be added to the post-anoxic tank 330 toincrease the BOD:N ratio. Such addition may occur by way of a carbondosing pump or other means. The amount of added carbon must be carefullycontrolled, as too much added carbon introduces an unacceptable BOD intothe effluent, while too little leaves some nitrates under-nitrified.Process measurements, such as flow and COD loading, are taken todetermine the amount of carbon to be added.

The post-anoxic tank 330 may include the same or similar properties asthe pre-anoxic tank 310. For example, an industrial scale post-anoxictank may be about 10,000 gallons, without limitation. Moreover, thepost-anoxic tank 330 may include a submersible mix pump 331 for mixingof the tank contents.

It has been found that the particular arrangement of the pre-anoxic tank310, aeration tank 320, and post-anoxic tank 330 is beneficial, as thepre-anoxic tank 310 has the advantage of a higher denitrification ratewhile the nitrates remaining in the liquor passing out of the pre-anoxictank 310 can be denitrified further in the post-anoxic tank 330 throughendogenous respiration. However, other arrangements of anoxic/aerobictanks may be employed as desired or required. For example, any number ofaeration and anoxic tanks may be employed, and the order of such tanksmay be rearranged. In one alternative embodiment, the post-anoxic tank330 may be omitted. In that embodiment, treated water moves from theaeration tank 320 to the membrane separation system (FIG. 2 at 130)(discussed below).

A membrane separation system 130 (e.g., employing a membrane bioreactor340 or the like) is employed to reduce both BOD/COD and nitrogen fromthe treated water that passed through the anoxic and aerobic treatmentsystem 129 (that is, through tanks 310, 320, and 330). Suspendedbacteria and other particulate solids (i.e., mixed liquor) may beremoved from the treated water using a membrane separation system 130.There are many different options for a membrane separation system 130design, but a micro or ultrafiltration membrane bioreactor (“MBR”) 340is preferred to separate solids from treated effluent. Also, most of theCOD in the water is removed through microbial action in the MBR 340. Anexemplary MBR 340 includes a submerged membrane 341.

In one specific embodiment, the MBR 340 includes a hollow-fiber membranehaving fibers held in modular cassettes that are immersed directly intoa liquid. Each cassette includes a permeate header that is connected tothe suction side of a reversible rotary lob pump, which applies alow-pressure vacuum to draw treated effluent through the microscopicpores of the fibers in an outside-in flow path. This approach mayminimize energy demands and prevent particles from fouling and plugginginside the membrane fiber. One particular MBR thought to be useful inthe processes described herein is a Z-MOD™-L MBR manufactured by GEWater & Process Technologies. The Z-MOD™-L MBR includes a ZEEWEED® 500membrane.

The MBR 340 includes the membrane cassette 341 and tank internals,membrane air scour blower 342, mixed liquor recycle pump 343, permeatepumps, chemical feed systems, a main control panel, and/or otherinstrumentation. The system may be scalable such that cassettes may beadded or removed as necessary.

The MBR 340 may have bacteria macronutrients, such as but not limited tophosphorous, added thereto. Micronutrients may be added by directingboiler or cooling tower blow-down to the system along with a source ofalkalinity for pH control (nitrification consumes alkalinity).Generally, antifoam addition may be needed to control foaming, dependingon the characteristics of the distilled water. For example, boiling orcooling tower blow-down from the temperature control unit 205 with addedNaOH or KOH is stored in tank 357 and added by pump 352. An antifoamagent stored in tank 356 may be added to the MBR 340 by pump 351.

Different scouring and cleaning systems may also be employed to keep themembranes 341 of the MBR 340 clean depending on the system design. Forexample, in a submerged membrane design, the membrane may be cleanedusing an air scour system 342. In certain embodiments, the MBR 340 maybe cleaned in place using caustic and/or citric acid solutions.Accordingly, parallel membrane tanks may be provided such that one tankcan be taken offline for cleaning without stopping treatment.

As shown, mixed liquor may be recycled from the MBR 340 to thepre-anoxic tank 310 by way of the mixed liquor recycle pump 343. Therecycled material may be referred to as return activated sludge (RAS)and may be recycled to the pre-anoxic tank 310 to re-seed the newdistilled water entering the anoxic/aeration system. Excess wasteactivated sludge (WAS) may be removed from the system, such as throughvalve 355. Treated water passes from the MBR 340 to a storage tank 350.Although a treated water storage tank 350 is shown, this tank may beomitted and the permeate leaving the MBR 340 can be transferred directlyto an ion exchange system 131 and/or a reverse osmosis system 132.

Although permeate, or purified water, leaving the membrane separationsystem 340 may meet the limitations of Table 1, above, in certainsituations, additional processing may be required to further purify thewater. Referring back to FIG. 2, water leaving membrane separationsystem 130 may be introduced to an ion exchange system 131 and/or areverse osmosis system 132. These systems may be employed individuallyor in series to reliably remove varying concentrations of NH₃-N and/orNOR-N as well as trace levels of organic and inorganic materials.

FIG. 4 provides a schematic diagram of an ion exchange (IX) system 131in accordance with an exemplary embodiment of the present invention. Incertain situations, heterotrophic bacteria may inhibit the growth andactivity of nitrifying bacteria to consume ammonia. In this situation,ion exchange offers an alternative or additional method in the removalof ammonia ions. Ion exchange offers a number of advantages tobiological treatment alone, including the ability to handle spikes ininfluent ammonia levels or metals and the ability to operate over awider range of temperatures. In other situations, the distilled watermay contain barium concentrations which would exceed desired effluentquality or potentially harm the reverse osmosis membranes.

Referring to FIG. 4, water from the treated water storage tank 350 isintroduced to an ion exchange column 410. Although a treated waterstorage tank 350 is shown, this tank may be omitted and the permeateleaving the MBR 340 can be transferred directly to the ion exchangecolumn 410. The pH of water exiting the treated water storage tank 350be adjusted by adding sodium hydroxide from tank 405 by a pump 407.

The IX column 410 is typically operated until break-though. In oneexemplary embodiment, the IX column 410 is actually two columns arrangedin series in a lead/lag configuration. In a lead/lag the primary bedreceives the contaminated water. This initial column the contaminant orcontaminants of concern, usually to acceptable levels itself. The secondcolumn acts as a safeguard against contaminants remaining in the waterfollowing break-through of the primary column. Upon break-through, theprimary column is regenerated and placed back into service, typically asthe secondary column, with the secondary column now becoming the primarycolumn. In an alternative embodiment, the system 131 includes two ormore sets of ion exchange columns 410 that operate in parallel, witheach set including a primary and secondary column in a lead/lagconfiguration. With a parallel arrangement, sets of columns can be takenoffline to regenerate without stopping the process.

FIG. 5 provides a schematic diagram of reverse osmosis system 132 inaccordance with an exemplary embodiment of the present invention. Waterfrom the treated water storage tank 350 is introduced into a mixer 510to adjust the pH of the water. The pH of the water is adjusted to lessthan about 6.0 by adding, for example, H₂SO₄ or HCl stored in tank 502and added by pump 503 and mixing in mixer 510. The pH adjustment stepmay be employed when the removal of NH₃—N is required to ensure thatNH₃—N remains as ions and does not enter the gaseous phase.

An anti-scaling additive stored in tank 506 may be added to thepH-adjusted liquid through pump 507, and then liquid passed through a1-micron pre-RO filter 515. The filtered liquid is then introduced to areverse osmosis vessel 525 using a high-pressure reverse osmosis feedpump 520.

The reverse osmosis vessel 525 forces water from a region of high soluteconcentration through a semipermeable membrane to a region of low soluteconcentration by applying a pressure in excess of the osmotic pressure.In certain embodiments, the reverse osmosis membrane(s) employed includea dense layer in the polymer matrix (e.g., skin of an asymmetricmembrane or an interfacial polymerized layer within athin-film-composite membrane). The membrane may be designed to allowonly water to pass through the dense layer, while preventing the passageof solutes. In one embodiment, the reverse osmosis includes a“sacrificial” member to increase recovery.

The reverse osmosis vessel 525 includes a number of modular “plug andplay” reverse osmosis skids having any number of thin-film compositereverse osmosis membranes. The system includes one or more trains havingmultiple membranes that may be added or removed based on the amount ofwater to be processed. In one specific example, thirty-six (36) reverseosmosis membranes may be employed.

The reverse osmosis vessel 525 include a clean-in-place (CIP) system530. The CIP system circulates cleaning liquids in a cleaning circuitthrough the reverse osmosis system. In certain embodiments the CIPsystem 530 may be skid-mounted. Through this cleaning process, trappedcontaminants are removed from the reverse osmosis vessel 525 membranes.

The trapped materials removed from the reverse osmosis vessel 525membranes may be recycled from the reverse osmosis vessel 525 to theanoxic and aerobic treatment system (FIG. 2 at 129). Specifically, thetrapped materials removed from the reverse osmosis system 525 membranesmay be used to re-seed the pre-anoxic tank (FIG. 3 at 310) (or removedfrom the system as waste or returned to the head of the pretreatmentsystem (see FIGS. 1A and B).

Upon exiting the reverse osmosis vessel 525, the water may require pHelevation to ensure the pH is from about 6.0 to about 8.0, preferablyabout 7.0. To that end, the water may be passed through a pH adjustmentsystem, which may include a metering pump 505 controlled by a downstreampH probe and an inline flash mixer 535. A base, such as but not limitedto NaOH, may be added to the water from tank 501 and mixed with mixer535.

The processed water may also require re-mineralization to preventcorrosion of downstream pipes, tanks, trucks, etc. As shown, brine froma brine tank 545 may be pumped using pump 547 and mixed into the water.The re-mineralized water is then stored in, for example, a pure waterstorage tank 540 before being shipped to an end user.

Either the ion exchange system 131, the reverse osmosis system 132, orboth may be used to further treat the treated water that exits the MBR340. The decision as to which system to employ may depend on economicfactors and/or technical factors.

Referring back to FIG. 2, effluent water exiting the ion exchange system131 or reverse osmosis system 132 may meet or exceed each of therequired properties shown in Table 1, above. Accordingly, distilledwater having the properties of Table 2 may be passed through theillustrated processing steps to be transformed into de-wasted water(water that can be managed in fresh water impoundments). In certainembodiments, the de-wasted water resulting from the above describedtreatment process may not be considered a waste as defined in 25 Pa.Code § 287.1. Moreover, the de-wasted water may be reused at oil and gaswell sites such that a potential “closed loop” is created. In otherembodiments, the de-wasted water may be used in any number of otherapplications or may simply be discarded into the environment orotherwise handled as fresh water. Distilled water having up to about 600mg/L cBOD₅ may be processed using the methods described herein. ThecBOD₅ level may be reduce to less than about 10 mg/L, less than about 5mg/L, less than about 2.5 mg/L, or even less than about 1 mg/L.Distilled water having influent COD levels of less than about 8000 mg/Lmay be treated using the methods described herein. Such COD levels maybe reduced to less than about 20 mg/L, less than about 15 mg/L, lessthan about 10 mg/L, or even less than about 5 mg/L in de-wasted water.In some embodiments, the COD levels of a de-wasted water may be reducedby about 95% to 99% or greater as compared to COD levels of influentdistilled water.

In some embodiments, distilled water having influent NH₃-N levels of upto about 50 mg/L may be treated using the methods described herein. SuchNH₃-N levels may be reduced to less than about 2.0 mg/L, less than 1.5mg/L, less than 1.0 mg/L, or even less than about 0.5 mg/L. Similarly,the treatment methods may provide de-wasted water having effluent NOR-Nlevels of less than about 2.0 mg/L, less than about 1.5 mg/L, less than1.0 mg/L, or even less than about 0.5 mg/L from distilled water havingan influent NOR-N level of about 0.6 mg/L.

The TSS levels of an exemplary de-wasted water subjected to thedescribed treatment methods may be from about 0.1 mg/L to less thanabout 5 mg/L. In an exemplary embodiment, the TSS levels of a de-wastedwater may be from about 0.5 mg/L to less than about 2 mg/L, and moreparticularly less than about 1 mg/L. Such results may be obtained byprocessing distilled water having an influent TSS level of up to about15 mg/L, e.g., 10 mg/L or 5 mg/L.

In one exemplary embodiment, the system may be designed to handlemaximum flows and 75 percentile cBOD₅ and nitrogen concentrations, asshown in Table 2. Higher influent loadings may be managed throughequalization or diversion to a sewer. For example, the system may bedesigned to process up to about 300,000 gallons per day of distilledwater having a pH from about 8 to about 11. Exemplary systems arecompatible with distilled water having up to about 40 mg/L NH₃-N and upto about 60 mg/L total nitrogen at a temperature of from about 20 toabout 40° C.

Table 3, below, shows the influent parameters supported by an exemplarysystem according to the invention:

TABLE 3 Exemplary Influent Design Parameters for Biological SystemInfluent Parameters Average Maximum Design Basis Flow Rate (gpd) 126,000201,600 126,000 COD (mg/L) 750 1,250 2000 COD (lb/day) 788 2101 2101Total Nitrogen (mg/L) 70 75 120 Total Nitrogen (lb/d) 74 126 126 TotalPhosphorus (mg/L) <1 <1 <1 TSS (mg/L) 5 10 10 Alkalinity (mg/L) 260 260260 pH 8-11 Temperature 20-35° C.

Table 4, below, shows design parameters of an exemplary system accordingthe invention:

TABLE 4 Exemplary Design Parameters for Biological System Design DesignParameters Average Max Basis Anoxic Tank (gal) 15000 15000 15000 AerobicTank 1 (gal) 50000 50000 50000 Aerobic Tank 2 (gal) 50000 50000 50000Membrane Tanks (gal) 12230 12230 12230 HRT (h) 24.2 15.1 24.2 MixedLiquor Temp. (° C.) 20-34 20-34 20-34 Mixed Liquor Suspended Solids in8000 10000 10000 Aerobic Tank (mg/L) Mixed Liquor Volatile Suspended7420 9699 9810 Solids in Aerobic Tank (mg/L) Solids Retention Time (SRT)(d) 46.6 15.2 15.2 RAS Flow From Membrane 4.0 4.0 4.0 Tank (Q) SludgeWasting (gpd) (the excess 1730 @ 1% 5350 5300 @ growth that needs to beremoved @1.25% 1.25% from the system) Sludge Wasting/Influent Flow 1.4%2.7% 4.2% Diffusers Coarse Coarse Coarse Bubble Bubble Bubble MaxProcess Air Flow (scfm) 700 1490 1500 (for aeration tank)

Although any known methods may be employed to determine whether theresultant de-wasted water meets the limitations of Table 1, in oneembodiment, such a determination is made according to one or more of thefollowing:

-   -   (a) A minimum of 14 consecutive daily flow proportional        composite samples analyzed for strontium, barium and TDS;    -   (b) A minimum of 2 weekly flow proportional composite samples        which are taken a minimum of 7 days apart analyzed for all        constituents listed in Table 1 except ammonia, benzene,        methanol, and toluene; and    -   (c) A minimum of 2 grab samples taken a minimum of 7 days apart        analyzed ammonia, benzene, methanol, and toluene.

Moreover, once a de-wasted water is stored, it may be tested todetermine whether it continues to meet the limitations of Table 1, by:

-   -   (a) Collecting daily flow proportional composite samples and        analyzing them for strontium, barium and TDS;    -   (b) Collecting weekly flow proportional composite samples and        analyzing them for all constituents listed in Table 1 except        ammonia, benzene, methanol and toluene.    -   (c) Collecting weekly grab samples and analyzing them for        ammonia, benzene, methanol and toluene.        Of course, modifications of the above testing methods may be        implemented if desired or required.

Analytical methodologies used to determine whether a de-wasted watermeets the requirements of Table 1 may include, but are not limited to,those in the Environmental Protection Agency's (“EPA”) “Test Methods forEvaluating Solid Waste, Physical/Chemical Methods” (EPA SW-846),“Methods for Chemical Analysis of Water and Wastes” (EPA 600/4-79-020),“Standard Methods for Examination of Water and Liquid Waste” (preparedand published jointly by the American Public Health Association,American Water Works Association, and Water Pollution ControlFederation), the Pennsylvania Department of Environmental Protection's“Sampling Manual for Pollutant Limits, Pathogens and Vector AttractionReductions in Sewage Sludge” or any comparable method subsequentlyapproved by the EPA or Department of Environmental Protection. Each ofthese documents is incorporated herein by reference in its entirety.

FIGS. 6A and B provide a detailed description of one embodiment ofevaporation/crystallization unit 125. In the embodiment shown,evaporation/crystallization unit 125 is an MVR crystallization plant.Accordingly, FIGS. 6A and B provide a detailed description of theoperation of evaporation/crystallization unit 125 along withconcentrated brine storage (FIG. 1B at 136). From FIGS. 1A and B, brinefrom pretreated wastewater storage tanks 124 c, 124 d passes toevaporation/crystallization unit 125 via pipe 133. Similarly, wash waterfrom distilled water storage tank 127 passes toevaporation/crystallization unit 125 via pipe 134.

Although the evaporation/crystallization unit 125 is shown integratedinto the treatment facility shown in FIGS. 1A and B, it is understoodthat it could be a standalone facility or incorporated into a number ofdifferent treatment facility designs.

In one embodiment, wastewater (feed brine) is pumped continuously fromthe treatment facility through pipe 133 into the evaporation/crystallization plant 125.

The feed brine received by evaporation/crystallization plant 125 may besplit into two streams. One stream may pass through the preheater 602where it is heated by low temperature vapor condensate coming frompreheater 610. Optimally, the wastewater stream passing though preheater602 should be heated to a temperature in the range of around 122° F.After preheater 602 the feed brine is fed to the filtrate tank 604 whereit is mixed with filtrate coming from the centrifuge 606. The mixture offiltrate and preheated feed brine is then pumped by pumps 608 fromfiltrate tank 604 to a second preheater 610. The brine passes throughthe second preheater 610. The second preheater 610 heats the feed brineusing hot vapor condensate from condensation tank 614, which receiveshot vapor from heating chest 620. Alternatively, other heaters may beused that do not rely on hot vapor from heating chest 620. Thepreheaters 602 and 610 can be washed periodically with condensate todissolve incrustations. Therefore, both heat exchangers 602 and 610 canbe by-passed as needed for maintenance. The preheated brine from theheat exchangers 602 and 610 passes through a control valve and intocirculation piping 612. Optimally, preheated feed brine enterscirculation piping 612 in the temperature of around 202° F.

The second stream of wastewater from pipe 133 may be used to regulatethe temperature of the washing brine sent to salt leg 624. Optimally,the temperature of the washing brine should be less than 122° F.

Preheated feed brine and filtrate entering circulation pipe 612 is mixedwith the evaporation brine that circulates in the circulation pipe ofevaporator 616 (contains approx. 20% of crystals NaCl). The mixed brineis pumped by circulation pump 618 into the heating chest 620. In optimalconditions, the mixed brine will be in the temperature range of 255° F.By flowing through the tubes of heating chest 620, the mixture is heatedup before entering evaporator 616 through a central inlet pipe. On thesurface of the liquid level in evaporator 616 the overheated brinereleases energy by flashing. Evaporated water exits the top ofevaporator 616. Brine droplets carried by the evaporated water areseparated by the demister 622 before the vapor is fed to therecompression group. In one embodiment, vapor exits the evaporator 616at around 230° F. Due to the increase in temperature while passingthrough heating chest 620 and subsequent flashing in evaporator 616, theconcentration of NaCl in the mixed brine in the evaporator bodyincreases above the saturation point. Once above the brine saturationpoint, NaCl crystallization begins, and existing NaCl crystals growlarger. The smaller NaCl crystals are recycled into the circulation loopthrough circulation pipe 612. Larger NaCl crystals settle down incounter current flow of fresh feed and are washed from the purge in thesalt leg 624. The small crystals do not settle down and are fluidizedback to the evaporator 616 by the elutriation brine.

A certain amount of brine together with small seeding crystals leavesthe evaporator 616 through the separation zone which is a part of thecirculation pipe 612.

The collected salt in the salt leg 624 is treated with elutriation brineto:

-   -   replace mother liquor carrying a higher concentration of        impurities (in solution),    -   flush back fines (NaCl solids) to the evaporator body,    -   enable further growing of small crystals,    -   fluidize the salt bed in the salt leg,    -   dilute the slurry for discharging to the centrifuges and    -   cool down the slurry to a lower temperature which is appropriate        for solid liquid separation in pusher type centrifuges and for        further salt transport on conveyors belt.

Vapor from the evaporator 616 is circulated from the evaporator 616 tothe demister 622. Droplets of brine carried in the vapor are separatedby the demister 622. The vapor in demister 622 flows through the set ofcorrugated plates, where brine droplets separate from the vapor phase atthe plate walls. After flowing through demister 622, vapor passes torecompression group, blowers 626, 628, and 630. Recompression blowersincrease the pressure and temperature of the vapor. In one embodiment,vapor temperature exiting the recompression group is around 269° F. andpressure is approximately 41 psi. Vapor from the recompression blowersis then passed to the heating chest 620 where it is condensed.

The demister 622 is periodically cleaned by vapor condensate deliveredby pumps 632. The vapor condensate is sprayed by cleaning nozzles. Thewashing condensate is returned by free flow to evaporator 616.

Vapor condensate is partially reused to de-superheat recompressed vaporsby means of the vapor condensate pumps 632 to supply the spray nozzlesin recompression blowers 626, 628, and 630, as well as the cleaningnozzle of 622. Provision is made to dose NaOH-solution to neutralize thevapors coming from evaporator 616.

As the plant will be operated with wastewater with fluctuatingcomposition, provision to dose NaOH is incorporated on demister 622.Caused by the high temperature in the evaporator body and presence ofsome salts, HCl may form in the brine slurry. This HCl will also betransported by vapors to the vapor demister 622 and downstream equipmentlike the blowers. To protect this equipment against corrosion by the HClone embodiment includes an option to add NaOH to neutralize the HCl. A5% w/w NaOH solution may be sprayed into the vapor duct right after thedemister 622.

Vapors may be recompressed by three blowers 626, 628, and 630 in series.The three blowers connected in series increase the pressure of the vaporin order to recover energy for further evaporation. Although threeblowers are shown, one skilled in the art understands that any number ofblowers may be used. Compressed vapor is condensed by the same wastewater from which it originates at a higher pressure and temperature. Thesaturation temperature of the recompressed vapor is higher than thetemperature of the brine slurry which is circulated in the evaporationsystem in circulation pipe 612, and therefore the compressed vapor canbe used to heat the circulating brine slurry. Vapor condenses on theshell side of the heating chest 620. Before the compressed vapor entersthe heating chest 620, condensate is sprayed into the vapor lines (622,626, 628, and 630) to decrease the temperature to the saturationtemperature and increase heat transfer in heating chest 620.

The suction lines of all blowers are drained via steam traps. Oneskilled in the art appreciates the evaporation load can be regulated byadjusting a variable frequency drive.

Low pressure steam at 22 psig (1.5 barg) is used for start-up of theplant and to make up the pressure in the system if the feed is too cold.Vapor condensate coming from heating chest 620 and steam condensate arecollected in condensation tank 614.

From the condensation tank 614, the steam condensate is pumped throughthe preheaters 610 and 602 by means of condensate pumps 632. Condensatepumps 632 are redundant and typically operate with one on standby.

The condensate pumps 632 are also used to supply cleaning nozzles of thedemister 622 and to de-superheat the vapors leaving the recompressionpumps 626, 628, and 630 before the vapor is sent to the heating chest620. After recovery of the heat in the brine preheaters the vaporcondensate is sent to the battery limit or the wash water tank 634.

Vapor condensate coming from condensation tank 614, after passingpre-heaters 610 and 602, is also used to supply sealing water tank 636and to dilute mother liquor before the purge is sent out of batterylimits.

The air and vapors mix affects the heat transfer by accumulatingnon-condensable air (i.e., air that has entered the system and dissolvedinto the feed brine) in heat exchangers. Therefore, the heating chest620 is continuously vented via restriction orifice mounted on the top ofventilation line.

NaCl slurry withdrawn from the salt leg 624 is discharged continuouslyto the centrifuge 606.

The centrifuge 606 separates salt crystals from brine. The salt crystalsfrom the centrifuges are transported by means of reversible chutes andput on the conveyor belt 638 and transported to the salt storage and/orsalt management facilities. The filtrate flows into the filtrate tank604. From there, it is pumped together with the feed brine via pump 608to the preheater[s] 610.

In the centrifuges, the cake of salt crystals can be further upgraded byspraying condensate to wash off mother liquor from the surface of thecrystals. This increases the purity of the product. In one embodiment,saturated low-pressure steam 22 psig (1.5 barg) from the battery limitis made available to the MVR plant for heating of heating chest 620during start-up of the MVR part of the plant and to make up heatingduring normal operation in heating chest 620 if more heat is requiredthan provided by the blowers.

Steam condensate is mixed with vapor condensate and collected incondensation tank 614. Condensate from condensation tank 614 is pumpedby means of pump 632 to heaters 610 and 602 to pre-heat the feed brinewhich is pumped counter currently from pipe 133 to circulation pipe 612.Pump 632 supplies the sealing water tank 636 and the wash water tank 634with condensate. The condensate is used as wash water and flush water.Pump 640 is used to supply wash water and seal water to variousconsumers. It also supplies hose connections to flush pipelines andequipment manually. Pump 640 supplies brine pumps with sealing water.The quality of the condensate is monitored by a conductivity meter.Condensate having very high conductivity can be accumulated in washwater tank 634 and send out of the plant from there.

Wash water supplied by pump 640 may be used to flush salt slurrypipelines, to flush sight glasses, to fill siphons, and to flush thecentrifuge 606.

The process water has to have drinking water quality and can be usedindependently from the production plant. This is, because it is used forthe eye wash and shower stations. The process water is additionally usedto feed the sealing water tank 636 if there is not enough vaporcondensate available.

Sealing water is taken from the sealing water tank 636 by means of pumps640 and fed into the sealing water piping system. Strainers associatedwith pump 640 remove dirt from the sealing water to avoid clogging ofsmall pipes in the sealing water system. Tank 636 is fed by vaporcondensate with pump 632. If there is too little vapor condensateavailable, the sealing water tank will be filled up by process water.

Pumps 640 operate as a pair, with one on standby. If one pump fails, thesecond one will start automatically.

Sealing water is supplied to pumps that handle hot brine or slurry, thesensing lines of pressure/level instruments, and circulation pump 618.

Cooling water from battery limit is used to cool the oil of thecentrifuge 606.

Instrument air is used for those components that are drivenpneumatically in the plant, such as the actuators of the control valves.

Utility stations shall be foreseen on each level at central positions ofthe plant. Connections for pressurized air and process water arerequired.

In case of electrical power failure, the circulation pipe 612 must bedrained of crystals as soon as possible. To keep crystals fluidizeduntil a drain operation is completed, an emergency pump or pumps areprovided. Emergency pumps keep the crystals near pump 618 fluidized,until the shut down or restart of the system is completed.

EXAMPLES

An exemplary pilot-sized distilled water processing system was testedwith an oil and gas liquid waste distillate. A schematic of the pilotsized plant 700 is illustrated in FIG. 7. As shown, the pilot plantincluded a 64-gallon pre-anoxic tank 710, a 210-gallon aeration tank720, a 65-gallon post-anoxic tank 730, a 90-gallon MBR 740, and an ionexchange system 745. The total volume of the pilot system was about 420gallons. Distilled water from tank 705 is pumped via pump 706 throughstrainer 707 (less than one-eighth inch mesh) to the pre-anoxic tank710. The pre-anoxic tank 710 includes a submersible pump 712 to mix thetank. Phosphorus, as phosphoric acid, is added from tank 714 to thepre-anoxic tank 710.

Treated water passed from the pre-anoxic tank 710 to the aeration tank720. Air is added to the aeration tank 720 using aeration blower 722.Nitrates are recycled from the aeration tank to the pre-anoxic tank 710by the nitrate recycle pump 724.

Treated water then passes to the post-anoxic tank 730. Carbon is addedusing a carbon source from tank 734 through carbon dosing pump 736. Thepost-anoxic tank 730 includes a submersible pump 732 to mix the tankcontents. A recycle pump 742 transfers the treated water into themembrane tank 740. Air from an aeration blower 744 is used to scour themembranes.

Permeate is sent from the membrane tank 740 through an ion exchangesystem 745 and into an effluent container 750. Pump 743 removes thepermeate from the membrane tank 740. Solids are removed to a batch WAScontainer 746 or gravity feed back to the pre-anoxic tank 710.

A seed sludge was obtained from a municipal sewage plant and screened toless than 3 mm before adding to the pre-anoxic tank 710 of the pilotplant. The pilot system was then operated with influent distilled waterfalling within the parameters shown in Table 2 above for approximately 2months for the bacteria in the process to acclimate to the specificwastewater characteristics and reach “steady state.” The pilot systemwas run multiple times from October 2011 to at least March of 2012, andthe performance of the system is shown graphically in FIGS. 8-10. FIG. 8depicts a graph 800 illustrating the chemical oxygen demand values forthe influent, effluent, and loading for an operation of a pilot plant700 in accordance with the wastewater treatment process depicted in FIG.7 and employing ion exchange. FIG. 9 depicts a graph 900 illustratingthe ammonia values for the influent and effluent for an operation of apilot plant 700 in accordance with the wastewater treatment processdepicted in FIG. 7. FIG. 10 depicts a graph 1000 illustrating thenitrate values for the effluent for an operation of a pilot plant 700 inaccordance with the wastewater treatment process depicted in FIG. 7.

Referring to FIG. 8, the COD concentration of the influent waterentering the pilot system and the effluent water exiting the pilotsystem are shown. Upon the addition of an ion exchange system to thepilot plant, the COD concentration of the effluent water was found to beconsistently less than about 20 mg/L.

Referring to FIG. 9, the NH₃-N concentration of the influent waterentering the pilot system and the effluent water exiting the pilotsystem are shown. Upon the addition of an ion exchange system to thepilot plant, the NH₃-N concentration of the effluent water was found tobe consistently less than about 2.0 mg/L.

Referring to FIG. 10, the NO₃-N concentration of the influent waterentering the pilot system and the effluent water exiting the pilotsystem are shown. Upon the addition of an ion exchange system to thepilot plant, the NO₃-N concentration of the effluent water was found tobe consistently less than about 2.0 mg/L.

FIG. 11 presents a process flow diagram for a wastewater treatmentprocess 1100 in accordance with an exemplary embodiment of the presentinvention. Referring to FIGS. 1A and B, 2, 3, 4, 5, and 10, at step1105, the pre-anoxic tank, such as pre-anoxic tank 310, is seeded withactivated sludge. This sludge includes bacteria and othermicro-organisms that remove nitrogen from a waste stream throughmicrobial action.

At step 1110, a distilled water product enters a temperature controlsystem, such as temperature control system 205, where the temperature ofthe distilled water product is adjusted to between 20° C. to 35° C. Thedistilled water product may be the result of pretreating and distillingwastewater from oil and natural gas production. In some cases, thetemperature of the water will need to be increased to satisfy thetemperature range of between 20° C. to 35° C. In most cases, thetemperature will need to be lowered. In still some cases, thetemperature of the distilled water product will be within the desiredtemperature range without adjustment.

At step 1115, the distilled water product is pre-filtered, or screened,to remove solids from the distilled water. Such as by pre-filter 210.The screen mesh size ranges from a mesh size capable of removingparticles of at least 1/20 inch in size to a mesh size capable ofremoving particles greater than about 1/4 inch in size.

At step 1120, the distilled water product is introduced into thepre-anoxic tank. Once in the tank, microbes contained in the tank digestnitrogen-containing compounds in a denitrification process underanaerobic conditions. Phosphorus, such as in the form of phosphoricacid, may be added to the pre-anoxic tank to provide nutrients for themicro- organisms. Nitrogen gas is released out of the pre-anoxic tank.

At step 1130, the water treated in the pre-anoxic tank is transferred toan aeration tank, such as aeration tank 320, where nitrogen compoundsare nitrified by bacteria under aerobic conditions. Air is provided tothe tank to facilitate the microbial action. Nitrates from the aerationtank are recycled to the pre-anoxic tank at step 1135.

At step 1140, the water treated in the aeration tank is transferred to apost-anoxic tank, such as post-anoxic tank 330, to remove residualnitrate by denitrification. If necessary, additional carbon is added tofacilitate the nitrate removal process. Micro-organisms in the waterperform the denitrification under anaerobic conditions.

At step 1150, the water treated in the post-anoxic tank is transferredto a membrane separator, such as membrane bioreactor 340. At this step,microbial action continues on the input side of the membrane. Thetreated water is forced through the membrane, removing the micro-organisms and other solids from the treated water. The permeate - thepurified water that has passed through the membrane—is collected forfurther treatment.

At step 1160, the permeate from the membrane bioreactor is furthertreated in a reverse osmosis system or an ion exchange system.

At step 1165, the membrane of the membrane bioreactor is scoured by airto remove the trapped materials, which may be recycled into thepre-anoxic tank as a source of activated sludge.

At step 1170, the water treated in the ion exchange system and/orreverse osmosis system is collected and tested to demonstrate compliancewith de-wasted water criteria. The water, once demonstrated to bede-wasted water, may be reused.

It is understood by those skilled in the art that the drawings arediagrammatic and that further items of equipment such as reflux drums,pumps, vacuum pumps, temperature sensors, pressure sensors, pressurerelief valves, control valves, flow controllers, level controllers,holding tanks, storage tanks, and the like may be required in acommercial plant.

What is claimed is:
 1. A system for treating wastewater comprising: awastewater input line for receiving wastewater comprising aconcentration of total dissolved solids (“TDS”) that is greater than150,000 mg/L: a pretreatment system configured to pretreat thewastewater from the wastewater input line to produce a pretreatedwastewater suitable for crystallization/evaporation; anevaporation/crystallization unit configured to produce, from thepretreated wastewater, a distilled water, a concentrated brinecomprising CaCl₂, and a salt slurry comprising NaCl; a purificationsystem configured to receive a first portion of the distilled water fromthe evaporation/crystallization unit and remove contaminants therefromto produce a purified water; and a post-treatment system comprising atleast one of an ion exchange system and a reverse osmosis system, thepost-treatment system configured to convert the purified water from thepurification system into a de-wasted water.
 2. A system according toclaim 1, further comprising a centrifuge configured to: receive the saltslurry produced by the evaporation/crystallization unit; and dewater thesalt slurry to produce a centrate/filtrate and a sodium chloride productcomprising NaCl crystals.
 3. A system according to claim 2, furthercomprising a circulation line connected to the centrifuge and theevaporation/crystallization unit, the circulation line configured toroute back to the evaporation/crystallization unit the centrate/filtrateproduced by the centrifuge.
 4. A system according to claim 3, whereinthe centrate/filtrate from the circulation line is mixed with thepretreated wastewater as the pretreated wastewater is fed to theevaporation/crystallization unit.
 5. A system according to claim 2,wherein the sodium chloride product comprises greater than 98% w/w NaCl.6. A system according to claim 1, further comprising a washer systemconfigured to: receive a second portion of the distilled water from theevaporation/crystallization unit; and wash the salt slurry with thesecond portion of the distilled water.
 7. A system according to claim 1,wherein the evaporation/crystallization unit is further configured toproduce a vapor comprising liquid droplets.
 8. A system according toclaim 7, further comprising a demister configured to remove the liquiddroplets from the vapor to produce a demisted vapor.
 9. A systemaccording to claim 8, further comprising a compression unit configuredto compress the demisted vapor to produce a compressed vapor.
 10. Asystem according to claim 9, further comprising a heating chestconfigured to receive the compressed vapor from the compression unit.11. A system according to claim 10, further comprising a circulationline configured to: receive a second portion of the distilled water fromthe crystallizer/evaporator unit; and circulate the second portion ofthe distilled water from the crystallizer/evaporator unit, through theheating chest, and back into the crystallizer/evaporator unit.
 12. Asystem according to claim 1, further comprising a second stage thermalmechanical evaporation/crystallization unit configured to: receive theconcentrated brine produced by the evaporation/crystallization unit; andproduce a high-purity calcium chloride product from the concentratedbrine.
 13. A system according to claim 12, wherein the high-puritycalcium chloride product comprises approximately 35% w/w CaCl₂.
 14. Asystem according to claim 13, wherein the concentrated brine comprisesapproximately 18% to 20% w/w CaCl₂.
 15. A system according to claim 12,wherein the second stage thermal mechanical evaporation/crystallizationunit is further configured to generate solid crystals from theconcentrated brine, the solid crystals comprising one or more of:barium, strontium and sodium.
 16. A system according to claim 12,further comprising a lithium removal system configured to remove lithiumfrom the concentrated brine before the concentrated brine is received bythe second stage thermal mechanical evaporation/crystallization unit.17. A system according to claim 1, wherein theevaporation/crystallization unit is a mechanical vapor recompression(“MVR”) crystallizer.
 18. A system according to claim 1, wherein thepretreatment system comprises one or more of: a pH adjustment/chemicaladdition tank, a flocculation tank, a clarifier, and an equalizationtank.
 19. A system according to claim 1, wherein the purification systemcomprises: an anoxic treatment system configured to denitrify nitrogencompounds in the first portion of the distilled water under anaerobicconditions to produce a denitrified distilled water therefrom; anaerobic treatment system configured to nitrify additional nitrogencompounds in the denitrified distilled water under aerobic conditions toproduce a nitrified distilled water therefrom; and a membrane separationsystem comprising a membrane, the membrane separation system configuredto remove the contaminants from the nitrified distilled water to producethe purified water.
 20. A system according to claim 1, wherein thede-wasted water comprises a chemical oxygen demand (“COD”) of less thanor equal to 15 mg/L, a methanol concentration of less than or equal to3.5 mg/L, a nitrite-nitrate nitrogen concentration of less than or equalto 2 mg/L, a sodium concentration of less than or equal to 25 mg/L, aTDS concentration of less than or equal to 500 mg/L, and a totalsuspended solids (“TSS”) concentration of less than or equal to 45 mg/L.